The impact of vegetation changes on air quality and climate in East Asia

Changes in land cover can directly impact air quality because of its effect on precursor concentrations of tropospheric aerosols and ozone whose changes in concentrations may in turn have an important implication for regional climate. We investigate these relationships between vegetation change, aerosol and ozone air quality, and regional climate in East Asia using numerical models together with long-term observations over the past decade. For this purpose we conducted transient climate simulations using the National Center for Atmospheric Research (NCAR) coupled global climate model, Community Climate System Model version 3.0 (CCSM3) with the observed sea surface temperature (SST) from the NCEP reanalysis for 1997-2007. Simulated vegetation cover and surface temperature are evaluated by comparing with the observations from the MODIS satellite instrument and surface stations in East Asia. We then conduct full chemistry simulations using the GEOS-Chem 3-D global chemical transport model driven by the simulated meteorology from the CCSM3 for the same period. The trend of modeled biogenic emissions is examined and quantitatively compared with the space-based formaldehyde measurements. A comparison of the simulated ozone and aerosols concentrations between using the fixed versus using the transient anthropogenic emissions for the past 10 yrs is used to diagnose the effect of the past vegetation changes on air quality over East Asia. Finally we compute the radiative forcing of ozone and aerosols due to changes in biogenic emissions to examine the climate-chemistry interactions induced by the vegetation change and its resulting effect on climate.